#include <stdio.h>
#include <stdlib.h>

int main()
{
    int i;
    float sum;
    for(i=1;i<=100;i++)
    {

        if(i%2!=0)
            sum=sum+1.0/i;
        else
            sum=sum-1.0/i;
    }
    printf("sum=%f\n",sum);
    return 0;
}
